Contents

Abstract

Enterotoxigenic E. coli (ETEC) is a type of bacteria that can infect
both children and adults, causing diarrhoea. In particular, it affects
people in developing countries. However, it is also a major cause of
'travellers' diarrhoea' in people visiting or returning from regions
where this infection is common. It is transmitted from person to person
by eating or drinking unclean food or water. Typically it causes watery
diarrhoea, with abdominal pains and vomiting, that can last for several
days. Vaccines are being considered as a way to prevent diarrhoea caused
by ETEC bacteria. ETEC bacteria share some similarities with the
bacteria that cause cholera. In this review, we examined the
effectiveness of either vaccines designed to prevent cholera or vaccines
designed specifically to prevent ETEC infection for preventing ETEC
diarrhoea. We compared these vaccines against the use of a control
vaccine (either an inert vaccine or a vaccine normally given to prevent
an unrelated infection), no intervention, an alternative ETEC vaccine,
or a different dose or schedule of the same ETEC vaccine.

We examined the research published up to 07 December 2012. We included
24 randomized controlled trials and 53,247 participants in this review.
Four studies assessed the use of oral cholera vaccines to prevent
diarrhoea caused by ETEC and eight trials assessed the use of
ETEC-specific vaccines to prevent diarrhoea. Seven studies presented
data from field trials and four studies presented data from studies
where people were artificially infected with ETEC bacteria. Also, 13
trials gave safety and immunological data only.

There is currently insufficient evidence to support the use of the oral
cholera vaccine Dukoral® to protect travellers against ETEC diarrhoea.
Based on a single trial in people travelling from the USA to Mexico, the
oral cholera vaccine Dukoral® may have little or no effect in preventing
ETEC diarrhoea (one trial, 502 participants, low quality evidence). Two
earlier trials, one undertaken in an endemic population in Bangladesh
and one undertaken in people travelling from Finland to Morocco,
evaluated a precursor of the oral cholera vaccine Dukoral®. Short term
protection against ETEC diarrhoea was demonstrated, lasting for around
three months (RR 0.43, 95% CI 0.26 to 0.71; two trials, 50,227
participants). However, this vaccine is no longer available.

An ETEC-specific, killed whole cell vaccine, which also contains the
recombinant cholera toxin B-subunit, was evaluated in people travelling
from the USA to Mexico or Guatemala, and from Austria to Latin America,
Africa, or Asia. There were no statistically significant differences in
ETEC-specific diarrhoea or all-cause diarrhoea (two trials, 799
participants) found and the vaccine was associated with increased
vomiting (RR 2.0, 95% CI 1.16 to 3.45; nine trials, 1528 participants).
The other ETEC-specific vaccines in development have not yet
demonstrated clinically important benefits. Further research is needed
to develop safe and effective vaccines to provide both short and
long-term protection against ETEC diarrhoea.

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